This invention relates, generally, to innovations and improvements in the known "undercap" (also referred to as "undercup") method and apparatus for introducing volatile propellants in the liquid state into aerosol containers in which product to be dispensed has already been introduced. More particularly, the invention relates to improvements and innovations in the undercap method and apparatus whereby by use of purging techniques, the loss of residual liquid propellant may be substantially reduced. Further, the invention relates to a modification of the outer bell of an undercap crimper-propellant fill head whereby the efficiency of purging with a compressed gas is materially improved.
A wide variety of products have been long and widely available in aerosol packages or containers including such items as insecticides, paints, hair sprays, lubricants, flowable foods, etc. The art of filling aerosol containers with various products and introducing propellants thereinto is highly developed and high speed apparatus and equipment for performing the product and propellant filling operations is also highly developed and commercially available.
As is well known, after a product to be dispensed has been introduced into open aerosol containers, they are closed by means of closure caps on which are mounted dip tubes that extend down to adjacent the bottom interiors of the containers and manually operable, upwardly extending exterior dispensing valves. There are two general methods of charging the aerosol containers with volatile propellant which serves to dispense the product in spray or aerosol form through the exterior valves. One of the methods is the so-called "through the valve" method wherein the propellant is introduced through the exterior valve after the closure cap has been crimped or sealed to the mouth of the container. The second method is the so-called "undercap" method wherein the closure cap assembly is placed loosely on the mouth of a container filled with product and then a bell chamber is brought into sealing engagement with the top of the container including the closure cap and its assembled parts. The propellant charge is then introduced into the bell chamber so as to lift the closure cap and allow the propellant to flow into the mouth of the container. Thereafter, the closure cap is crimped into place. The present invention relates to the "undercap" method which is generally preferred for high speed/high volume production lines.
A number of patents have issued on the so-called "crimping" or "crimper" heads used in commercially practicing the undercap method of charging aerosol containers with volatile propellants including the following: U.S. Pat. No. 3,157,974 dated Nov. 24, 1964; U.S. Pat. No. 4,875,324 dated Oct. 24, 1989 and U.S. Pat. No. 4,938,000 dated Jul. 3, 1990. The crimper-propellant fill heads disclosed in these patents have been commercially produced by the assignee thereof, namely, The Kartridg Pak Co. of Davenport, Iowa. Customers of The Kartridg Pak Co. have used these machines in the United States and a number of foreign countries to produce large quantities of aerosol packages. The disclosures of the three above patents are incorporated herein by reference and made a part hereof.